package demo2;

// 循环队列
public class MyCircularQueue {

    private int[] elem;
    private int front;
    private int rear;

    public MyCircularQueue(int k) {
        elem = new int[k + 1];
    }

    // 入队
    public boolean enQueue(int value) {
        if (isFull()) {
            return false;
        }
        elem[rear] = value;
        rear = (rear + 1) % elem.length;
        return true;
    }

    // 出队
    public boolean deQueue() {
        if (isEmpty()) {
            return false;
        }
        front = (front + 1) % elem.length;
        return true;
    }

    // 获取队首元素
    public int Front() {
        if (isEmpty()) {
            return -1;
        }
        return elem[front];
    }

    // 获取队尾元素
    public int Rear() {
        if (isEmpty()) {
            return -1;
        }
        return elem[(rear - 1 + elem.length) % elem.length];
    }

    // 是否为空
    public boolean isEmpty() {
        return front == rear;
    }

    // 是否已满
    public boolean isFull() {
        //浪费一个空间来区分 队列空 和 队列满
        return (rear + 1) % elem.length == front;
    }
}
